Question

A parachutist whose mass 85 kg drops from a helicopter hovering 2500 m above the ground and falls toward the ground under the influence of gravity. Assume that the force due to air resistance is proportional to the velocity of the parachutist, with the proportionality constant b1=30 N-sec/m when the chute is closed and b2=100 N-sec/m when the chute is open. If the chute does not open until the velocity of the parachutist reaches 20 m/sec, after how many seconds will the parachutist reach the ground? Assume that the acceleration due to gravity is 9.81 m/sec^2.

Answer #1

An object of mass 120 kg is released from rest 480000 m above
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Assume the gravitational force is constant, with g=9.8
m/sec2 , and the force due to air resistance is
proportional to the velocity of the object with proportionality
constant k= 3 kg/sec. Approximate the speed (in m/sec) of the
object when it strikes the ground.

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ch 6
1:
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.
×10
J
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??...

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